1. Field of the Invention
Exemplary embodiments of the present invention relate to a medium access control method in a wireless LAN system using multiple channels; and, more particularly, to a medium access control method of an access point for providing a downlink service in a wireless LAN system using multiple channels.
2. Description of Related Art
There has been an ever-increasing demand for Internet availability, particularly through wireless LANs. A wireless LAN service is a service which provides an existing short-range wired communication service, i.e., a wired LAN service, by using a wireless medium as a data transmission medium. The Institute of Electrical and Electronics Engineers (IEEE) 802.11 Infrastructure scheme has been widely used as a wireless communication method. Wireless LAN technology has evolved into the IEEE 802.11n, which increases the data rate from the conventional level of tens of Mbps up to 600 Mbps.
A wireless LAN service enables a wireless station (STA), such as a notebook computer or a personal digital assistant (PDA), to receive a variety of services, e.g., a wireless Internet service, by using an access point which functions as a wired/wireless gateway. Specifically, a medium access control (MAC) protocol of a wireless LAN defined in the IEEE 802.11 basically supports a Basic Service Set (BSS) constituted by a wireless station and an access point which functions as an association point of a distributed system. The access point performs a function similar to a LAN hub. A single access point may provide a service to wireless stations placed in a preset service area. The service area refers to an area where the access point can provide a service to the wireless stations.
Recently, as wireless LAN users are rapidly increasing, there is a growing need for increasing data throughput which is provided in a single BSS, i.e., a wireless LAN system. To this end, much study has been conducted on systems which provide a wireless LAN service through multiple channels.